There has been known an automatic document feeder (“ADF”) equipped in an image-reading device and a sheet conveyor mechanism equipped in an image forming apparatus (hereinafter, there are referred to as a sheet conveyor device).
A known sheet conveyor device is configured to switch a conveying path to be used among a plurality of conveying paths in accordance with a thickness of a sheet to be conveyed. For example, in the known sheet conveyor device equipped in an image-reading device, a conveying path including a substantially U-shaped part in which a conveying direction of a document is reversed such that the document is substantially U-turned (hereinafter, referred to as a first conveying path) is used when a cover is closed. When the cover is opened, a conveying path through which a document is conveyed without being warped hardly (hereinafter, referred to as a second conveying direction) is used. The known sheet conveyor device is configured to convey a document without the cover being opened in most cases. When the cover is opened, the sheet conveyor device is configured to convey a relatively-thick tear-resistant sheet or a sheet to be damaged due to warping.
The known sheet conveyor equipped in the image-reading device includes a movable guide portion near a first conveyor roller pair disposed inside the cover. When the cover is closed, the movable guide portion is located at a position where an tip of the movable guide portion points diagonally downward (hereinafter, referred to as a first position). In this state, a sheet conveyed by the first conveyor roller pair is made contact with the movable guide portion and is further conveyed to the U-shaped part of the conveying path with being guided by a contact surface of the movable guide portion.
When the cover is opened, the movable guide portion is located at a position where the tip of the guide portion points diagonally upward (hereinafter, referred to as a second position). In this state, the sheet conveyed by the first conveyor roller pair is discharged onto an upper surface of the cover without being made contact with the movable guide portion.
As described above, the movable guide portion is configured to move between the first position and the second position in accordance with the opening or closing of the cover. Therefore, the sheet conveyor device may provide higher convenience as compared with a sheet conveyor device including a cover and a movable guide portion that are configured to be moved independently without synchronization.
However, the following problems may arise when the movement of a portion that may be openable like the above-described cover (hereinafter, referred to as an openable portion) and the movement of the movable guide portion are simply synchronized. That is, in the sheet conveyor device in which the openable portion and the movable guide portion are configured to be moved in synchronization with each other, the movable guide portion may be slightly moved toward the second position from the first position when the openable portion is slightly opened. Under this condition, when a sheet is conveyed from an upstream in the conveying path, the sheet may be made contact with the movable guide portion but may not be guided to an appropriate direction. As a result, a problem, for example, a paper jam, may occur in the conveying path.
When the openable portion rattles in some degree due to variations in assembling accuracy within tolerances, the movable guide portion may rattle due to the rattling of the openable portion. In this case, the movable guide portion may be moved toward the second position from the first position in accordance with an amount of rattling of the guide portion. In this case, also, a problem, for example, a paper jam, may occur in the conveying path.
Therefore, some arrangement may need to be adapted to avoid or reduce the above problem for synchronizing the movements of the openable portion and the movable guide portion. However, a detailed configuration for synchronizing the openable portion (the cover) and the guide portion in the known sheet conveyor may be unknown.